The present invention is related to printed circuit board technology and, more particularly, to bus structures for high speed operations with integrated circuits, particularly dynamic random access memory (DRAM) circuits, mounted on the printed circuit board.
Electronic systems are typically formed by integrated circuits mounted on printed circuit boards. The integrated circuits are interconnected by parallel signal line traces, called a bus, formed in or on the printed circuit board substrate which is formed from electrically insulating material, such as resin. If more than one board is required for the system, the signal lines on the board are connected to end tabs by which several printed circuit boards may be electrically interconnected to form a complete system. A common example of an electronic system with one or more printed circuit boards is a personal computer which has a mother board holding the microprocessor and other integrated circuits. Other circuit boards may be connected to the mother board to form the complete system.
In all electronic systems, high speed operation is desirable. However, high speed operation is not only limited by the operational speed of the constituent integrated circuits, but also by the fundamental characteristics of the printed circuit board buses over which the integrated circuits communicate. The characteristics include the raw bandwidth capability of the bus, the propagation delay of a signal from a driving component to a receiving component, signal integrity, noise immunity, skew, and so on.
The present invention is directed toward the achievement of a fast, robust bus structure on a printed circuit board for integrated circuits, particularly, dynamic RAMs.